In-Situ and Correlative Electron Microscopy

We compare, by in situ annealing of carbon nanofibres (CNFs) in the TEM, the catalytic activities of Ni and Fe for the nucleation of graphene layers. Graphene planes that are at an angle with the metal are dissolved in the case of Ni, while new graphene layers are generated parallel to the surface. In the case of Fe, we see no evolution of the particle in the same conditions, unless we start from an amorphized CNF. In that case, the amorphous carbon is easily dissolved into the Fe. These dissolved carbon atoms get out of the particle in the form of a new nanotube, where nucleation takes place - partly at least - perpendicular to the Fe surface.